Radiation Dose Reduction in Scoliosis Patients: Low-Dose Full-Spine Radiography with Digital Flat Panel Detector and Image Stitching System

Purpose: To evaluate the exposure dose reduction with a digital flat panel detector (FPD) and an image stitching system (ISS) in full-spine radiography for scoliosis patients. Materials and Methods: During a 6-month period, all consecutive scoliosis patients with a clinical indication for full-spine radiography (n = 50) were examined with an FPD and ISS. Automatic exposure control adjusted to speed class 1600 was used together with age-adjusted tube voltage and filtration. Dose area products were recorded for all images (antero-posterior n = 50, lateral n = 18). Images were evaluated by two radiologists for the possibility (possible, impossible) of typical scoliosis measurements (Cobb angle, Stagnara angle, lateral deviation, Risser stage). All measurements assessed as impossible underwent a second evaluation categorizing the reason why a measurement was impossible (underlying pathology, projection, image quality). Patient characteristics influencing exposure were recorded (sex, age, weight, height). Mean dose area products were compared to the literature with consideration of patient group and image quality. Results: The mean dose area product was 16.8 mu Gy m(2) for antero-posterior images and 26.6 mu Gy m(2) for lateral images. A comparison to published values showed an exposure dose reduction of 47% to 93%. Measurement of the Cobb and Stagnara angle, lateral deviation and Risser stage was possible in 96% (n = 50), 83% (n = 18), 100% (n = 50) and 100% (n = 50) of cases. The reasons for impossible measurements were independent of image quality (underlying pathologies, projection). Conclusion: When imaging scoliosis patients, an FPD combined with an ISS can substantially reduce the exposure dose.